[1] Frederick was born on 11 October 1671 at Copenhagen Castle as the eldest son of King Christian V and his spouse Charlotte Amalie of Hesse-Kassel.

But his visit there was cut short by a message telling of his brother Prince Christian's serious illness (he had, in fact, already died in Ulm).

[5] Frederick's most important domestic reform was the abolition in 1702 of the so-called vornedskab, a kind of serfdom which had applied to the peasants of Zealand since the Late Middle Ages.

His efforts were largely in vain because of the introduction in 1733 of adscription (stavnsbånd), a law that forced peasants to remain in their home regions, by which the peasantry were subjected to both the local nobility and the army.

Politically this period was marked by the King's connection to the Reventlows, the Holsteiner relatives of his second queen, and by his growing suspicion of the old nobility.

[7][8] During Frederick's rule Copenhagen was struck by two disasters: the plague of 1711, and the great fire of October 1728, which destroyed most of the medieval capital.

Frederick IV holds a memorable place in the social history of the city of Venice due to a remarkable visit he made during the winter of 1708–09.

He also made a visit to the dowager grand-princess Violante Beatrice at the grand-ducal court of the Medici family in Florence, further cementing his ties with the European nobility.

He was the penultimate Danish king to make a morganatic marriage (the last was Frederick VII with Louise Rasmussen aka "Countess Danner").

Frederick had seen Anne Sophie at a masquerade ball at Koldinghus, where the royal family resided during the plague that devastated Copenhagen.

Anna's sister, the salonist Countess Christine Sophie Holstein of Holsteinborg, was nicknamed Madame Chancellor because of her influence.

The other Schleswig-Holstein dukes of the House of Oldenburg perceived their interests to be injured, and Frederick found himself embroiled in complicated lawsuits and petitions to the Holy Roman Emperor.

[15] Also offended by the Countess's elevation were Frederick's younger unmarried siblings, Princess Sophia Hedwig (1677–1735) and Prince Charles (1680–1729), who withdrew from Copenhagen to their own rival court at the handsomely re-modelled Vemmetofte Cloister (later a haven for dowerless damsels of the nobility).

Despite the growing weakness, he set in 1730 on a muster travel; he reached Gottorp but had to return, and died in Odense, on the day after his 59th birthday.